%% mhchem.sty
%% Copyright 2004-2007   M.a-r.t-i.n   H.e-n.s-e.l
%
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License version 1.3c
% which can be found at
%   http://www.latex-project.org/lppl/lppl-1-3c.txt
%
% This work has the LPPL maintenance status "maintained".
% The Current Maintainer of this work is   M.a-r.t-i.n   H.e-n.s-e.l.
%
% ( In order to fight spam, the maintainer's contact      )
% ( information is "encrypted" with ROT13.                )
% ( If you do not know ROT13 yet and have no tool for     )
% ( decryption, simply do an Internet search for "ROT13". )
%
% ,---[ ROT 13 ]---
% | Gur Pheerag Znvagnvare bs guvf jbex vf Znegva Urafry
% |   jub pna or pbagnpgrq ivn
% |     zupurz@ZnegvaUrafry.qr
% |   be ivn znvy
% |     Znegva Urafry
% |     Cbfgfge. 20
% |     09232 Unegznaafqbes
% |     Treznal
% `----------
%
% This work consists of the files mhchem.sty, rsphrase.sty,
% mhchem.pdf and legal.txt.
%
%
\ProvidesPackage{mhchem}[2007/05/19 v3.07 for typesetting chemical formulae]
\RequirePackage{ifthen}
\RequirePackage{calc}[1998/07/07]
\RequirePackage{twoopt}
\RequirePackage{amsmath}
\RequirePackage{keyval}
\RequirePackage{graphics}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   misc    %%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\newcommand*\mhchem@cmath[1]{\ensuremath{\text{\ensuremath{#1}}}}%
\newcommand*\cmath[1]{\mhchem@cmath{#1}}%
\DeclareMathSymbol{\mhchem@hyphen}{0}{operators}{45}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   \cee   %%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\newcommand*{\cee}[1]{%
  \ifnum1<\mhchem@option@version%
    \def\mhchem@ce@out{}%
      {\mhchem@ce@v#1\mhchem@empty\\\mhchem@END\mhchem@ENDEND}%
    \ensuremath{%
	    \mhchem@ce@out%
	  }%
	\else%
	  \PackageWarningNoLine{mhchem}{%
      The \string\cee{} command of mhchem is only available\MessageBreak
      when you secify [version=2] or greater}%
	\fi%
}%

\def\mhchem@ce@v#1\\#2#3\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    \mhchem@ce@vii#1&\mhchem@END\mhchem@ENDEND%
  \else%
    \mhchem@ce@vii#1&\mhchem@END\mhchem@ENDEND%
    \g@addto@macro\mhchem@ce@out{\\}%
    \mhchem@ce@v#2#3\mhchem@ENDEND%
  \fi%
}

\long\def\mhchem@ce@vii#1&#2#3\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    \g@addto@macro\mhchem@ce@out{\ce@main{#1}}%
  \else%
    \g@addto@macro\mhchem@ce@out{\ce@main{#1}}%
    \g@addto@macro\mhchem@ce@out{&}%
    \mhchem@ce@vii#2#3\mhchem@ENDEND%
  \fi% 
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   \ce   %%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%

\def\mhchem@protect{\protect\noexpand\protect}%

\newcommand\ce[1]{\mhchem@ce@xiii{\mhchem@ce@viii#1 \mhchem@END\mhchem@ENDEND}}%
%
%
\def\mhchem@ce@viii#1 #2\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    \ifx\@empty#1\@empty
    \else
      \mhchem@ce@x#1\mhchem@END\mhchem@ENDEND%
    \fi
  \else%
    \mhchem@ce@x#1\mhchem@END\mhchem@ENDEND%
    \space\mhchem@ce@viii#2\mhchem@ENDEND%
  \fi
}
%\def\mhchem@ce@ix#1#2 #3\mhchem@ENDEND{%
%  \ifx\mhchem@END#3%
%    \ifx\mhchem@empty#2\mhchem@empty%
%      \mhchem@ce@x{#1}#2\mhchem@END\mhchem@ENDEND%
%    \else%
%      \mhchem@ce@x#1#2\mhchem@END\mhchem@ENDEND%
%    \fi%
%  \else%
%    \ifx\mhchem@empty#2\mhchem@empty%
%      \mhchem@ce@x{#1}#2\mhchem@END\mhchem@ENDEND%
%    \else%
%      \mhchem@ce@x#1#2\mhchem@END\mhchem@ENDEND%
%    \fi%
%    \ifx\mhchem@END#1\else%
%      \space\mhchem@ce@ix#3\mhchem@ENDEND%
%    \fi%
%  \fi%
%}
\def\mhchem@ce@x#1#2\mhchem@ENDEND{%
  \ifx\@empty#1\@empty%
    \mhchem@ce@xi{}\mhchem@END\mhchem@ENDEND%
  \else%\ifx\mhchem@END#1\else
    \mhchem@ce@xi#1\mhchem@END\mhchem@ENDEND%
  \fi%\fi%
  \ifx\mhchem@END#2%
  \else%
    \mhchem@ce@x#2\mhchem@ENDEND%
  \fi%
}
\def\mhchem@ce@xi#1#2\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    \ifx\@empty#1\@empty%
      {}%
    \else\if\noexpand#1##%
      \mhchem@protect\tbond%
    \else%
      \mhchem@protect#1%
    \fi\fi%
  \else%
    {\mhchem@ce@xii#1#2}%
  \fi%
}
\def\mhchem@ce@xii#1\mhchem@END{\mhchem@ce@viii#1 \mhchem@END\mhchem@ENDEND}%
\DeclareRobustCommand\mhchem@ce@xiii[1]{%
  \bgroup%
  \def\mhchem@protect{\noexpand}%
  \edef\mhchem@tmp{#1}%
  \expandafter\ce@main\expandafter{\mhchem@tmp}%
  \egroup
}


%%%

\DeclareRobustCommand*{\ce@main}[1]{%
	\bgroup%
  \ifnum1<\mhchem@option@version%
    \ifmmode\else\def\mhchem@option@alwaystextmode{1}\fi%
	\fi%
	\ifx\@empty#1\@empty\else%
	  \ifmmode\else\mhchem@option@textfont\fi%
	  \ensuremath{%
	    \mhchem@ce@xx#1 \mhchem@END\mhchem@ENDEND%
	  }%
	\fi%
	\egroup%
}%

\def\mhchem@ce@xx#1 #2\mhchem@ENDEND{%
  \mhchem@ce@i#1\mhchem@empty\mhchem@ENDEND%
  \ifx\mhchem@END#2%
  \else%
    \mhchem@ce@xx#2 \mhchem@ENDEND%
  \fi%
}
\def\mhchem@ce@i#1#2\mhchem@ENDEND{%
  \ifcat a#1 {\mhchem@ce@ii{#1#2}}%
  \else\ifx 1#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 2#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 3#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 4#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 5#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 6#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 7#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 8#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 9#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx 0#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx (#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx [#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx \{#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx ^#1{\mhchem@ce@ii{#1#2}}%
  \else\if ^#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx _#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx $#1{\mhchem@ce@ii{#1#2}}%
  \else\ifx -#1{\ifx\@empty#2\@empty#1\else\mhchem@ce@dash#2\mhchem@END\fi}%
  \else\if\noexpand#1<{\ifx\@empty#2\@empty#1\else\mhchem@ce@lt#2\mhchem@END\fi}%
  \else\ifx +#1+ \mhchem@ce@ii{#2}%
  \else\ifx \protect#1{\mhchem@ce@ii{#1#2}}%
  %
  \else\ifx\ce#1 \mhchem@ce@i #2 \mhchem@END%
  \else\ifx\cf#1 \cf{#2}%
  \else\ifx\cmath#1 \mhchem@ce@cmath#2\mhchem@END%
  %
  \else #1#2%
  \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi%
}

%
\def\mhchem@ce@dash#1#2\mhchem@END{%
  \if\noexpand#1>%
    {}\ifx\@empty#2\@empty\mhchem@gives#2%
    \else\mhchem@ce@deploycommand{mhchem@gives}#2{}\mhchem@END\fi{}%
  \else%
    -#1#2%
  \fi%
}%
\def\mhchem@ce@lt#1#2\mhchem@END{%
  \ifx =#1\mhchem@ce@equal#2\mhchem@END%
  \else\if\noexpand#1<\mhchem@ce@equiL#2\mhchem@END%
  \else\ifx-#1%
    \ifx\@empty#2\@empty%
      {}\mhchem@givesleft#2{}%
    \else%
      \mhchem@ce@dashtwo#2\mhchem@END%
    \fi%
  \else%
    <#1#2%
  \fi\fi\fi%
}
\def\mhchem@ce@equal#1#2\mhchem@END{%
  \if\noexpand#1>% (<=)>...
    \ifx\@empty#2\@empty{}\mhchem@equilibrium#2{}%
    \else%
      \mhchem@ce@equi#2\mhchem@END%
    \fi%
  \else%
    <=#1#2%
  \fi%
}
\def\mhchem@ce@equi#1#2\mhchem@END{%
  \if\noexpand#1>%
    {}\ifx\@empty#2\@empty\mhchem@equilibriumRight#2%
    \else\mhchem@ce@deploycommand{mhchem@equilibriumRight}#2{}\mhchem@END\fi{}%
  \else%
    {}\mhchem@ce@deploycommand{mhchem@equilibrium}#1#2{}\mhchem@END{}%
  \fi%
}
\def\mhchem@ce@equiL#1#2\mhchem@END{%
  \ifx =#1\mhchem@ce@equiLi#2\mhchem@END%
  \else<=#1#2%
  \fi%
}
\def\mhchem@ce@equiLi#1#2\mhchem@END{%
  \if\noexpand#1>% (<<=)>
    {}\ifx\@empty#2\@empty\mhchem@equilibriumLeft#2%
    \else\mhchem@ce@deploycommand{mhchem@equilibriumLeft}#2{}\mhchem@END\fi{}%
  \else%
    <<=#1#2%
  \fi%
}
\def\mhchem@ce@dashtwo#1#2\mhchem@END{%
  \if\noexpand#1>%
    {}\ifx\@empty#2\@empty\mhchem@mesomeric#2%
    \else\mhchem@ce@deploycommand{mhchem@mesomeric}#2{}\mhchem@END\fi{}%
  \else%
    {}\mhchem@ce@deploycommand{mhchem@givesleft}#1#2{}\mhchem@END{}%
  \fi%
}
\def\mhchem@ce@deploycommand#1#2#3\mhchem@END{%
  \ifx T#2\csname#1T\endcsname#3%
  \else\ifx C#2\csname#1C\endcsname#3%
  \else\csname#1\endcsname#2#3\fi\fi%
}

\def\mhchem@ce@ii#1{%
  \mhchem@ce@iii#1%
}
\newtoks\tok@mhchem@ce@iii%
\def\mhchem@ce@iii@tmp@i{}%
\def\mhchem@ce@iii@tmp@ii{}%
\def\mhchem@ce@iii#1\mhchem@empty{%
  \tok@mhchem@ce@iii{#1}%
  \edef\mhchem@ce@iii@tmp@i{\the\tok@mhchem@ce@iii}%
  %
  \def\mhchem@ce@iii@tmp@ii{(^)}%
  \ifx\mhchem@ce@iii@tmp@i\mhchem@ce@iii@tmp@ii%
    {}\mathop{\uparrow}{}%
  \else\def\mhchem@ce@iii@tmp@ii{^}%
  \ifx\mhchem@ce@iii@tmp@i\mhchem@ce@iii@tmp@ii%
    {}\mathop{\uparrow}{}%
  \else\def\mhchem@ce@iii@tmp@ii{(v)}%
  \ifx\mhchem@ce@iii@tmp@i\mhchem@ce@iii@tmp@ii%
    {}\mathop{\downarrow}{}%
  \else\def\mhchem@ce@iii@tmp@ii{v}%
  \ifx\mhchem@ce@iii@tmp@i\mhchem@ce@iii@tmp@ii%
    {}\mathop{\downarrow}{}%
  \else%
    \cf{#1}%
  \fi\fi\fi\fi%
}%

\def\mhchem@ce@cmath#1#2\mhchem@END{\mhchem@cmath{#1}\cf{#2}}

%%%%%%%%%%%%%
%%% arrows

\newlength{\mhchem@arrowminlength}
\setlength{\mhchem@arrowminlength}{1em}
%TODO: adapt min length to each of the math modes

%%% for font arrows
%%%%% idea taken from http://www.texnik.de/misc/harpoon.phtml
\def\mhchem@rightharpoonupfill@{\arrowfill@\relbar\relbar\rightharpoonup}
\def\mhchem@leftharpoondownfill@{\arrowfill@\leftharpoondown\relbar\relbar}
\newcommand*\mhchem@xrightleftharpoons[2][]{%
  \mathrel{%
  \rlap{\protect\raisebox{.22ex}{$\ext@arrow 3399\mhchem@rightharpoonupfill@{}{\mhchem@mathbox[#1]{#2}}$}}%
  \raisebox{-.22ex}{$\ext@arrow 3399\mhchem@leftharpoondownfill@{#1}{\hphantom{#2}}$}}}%
\newsavebox\mhchem@arrows@box%
\newcommand*\mhchem@xlongrightshortleftharpoons[2][]{\mathrel{%
  \sbox{\mhchem@arrows@box}%
    {$\mkern9mu\ext@arrow 3399\mhchem@leftharpoondownfill@%
     {#1}{\hphantom{#2}\mkern-6mu\mkern-12mu}$}%
  \rlap{\protect\raisebox{-.22ex}{\usebox{\mhchem@arrows@box}}}%     
  \protect\raisebox{.22ex}{$\ext@arrow 3399\mhchem@rightharpoonupfill@%
    {\hphantom{\usebox{\mhchem@arrows@box}}\mkern-6mu}{#2}$}%
  }}
\newcommand*\mhchem@xshortrightlongleftharpoons[2][]{\mathrel{%
  \sbox{\mhchem@arrows@box}%
    {$\mkern9mu\ext@arrow 3399\mhchem@rightharpoonupfill@%
     {\hphantom{#1}\mkern-6mu\mkern-12mu}{#2}$}%
  \rlap{\protect\raisebox{.22ex}{\usebox{\mhchem@arrows@box}}}%
  \protect\raisebox{-.22ex}{$\ext@arrow 3399\mhchem@leftharpoondownfill@%
    {#1}{\hphantom{\usebox{\mhchem@arrows@box}}\mkern-6mu}$}%
  }}
%\newcommand*\mhchem@xleftrightarrow[2][]{\ext@arrow 3095\leftrightarrowfill@{#1}{#2}}
  
  
%%% for pgf arrows
\newcommand*\mhchem@rightarrow@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex]
      (0cm,0.575ex) -- ++(#1,0cm)
      arc (250:198:0.6ex) arc (198:250:0.6ex)
      arc (110:162:0.6ex);
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftarrow@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex]
      (#1,0.575ex) -- (0cm,0.575ex)
      arc (70:18:0.6ex) arc (18:70:0.6ex)
      arc (-70:-18:0.6ex);
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftrightarrow@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex]
        (0cm,0.575ex) 
        arc (70:18:0.6ex) arc (18:70:0.6ex)
        arc (-70:-18:0.6ex) arc (-18:-70:0.6ex)
        -- ++(#1,0cm)
        arc (250:198:0.6ex) arc (198:250:0.6ex) 
        arc (110:162:0.6ex);
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftrightharpoon@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex]
        (0cm,0.575ex+0.22ex) -- ++(#1,0cm) arc (250:198:0.9ex);  
    \draw[cap=round, join=round, line width=0.09ex]
        (#1,0.575ex-0.22ex) -- ++(-#1,0cm) arc (70:18:0.9ex);
  \end{tikzpicture}%
}%      
\newcommand*\mhchem@longrightshortleftharpoons@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex]
        (0.0cm,0.575ex+0.22ex) -- ++(#1,0cm) arc (250:198:0.9ex);  
    \draw[cap=round, join=round, line width=0.09ex]
        (#1+0.5em-1em,0.575ex-0.22ex) -- (0.5em,0.575ex-0.22ex) arc (70:18:0.9ex);
  \end{tikzpicture}%
}% 
\newcommand*\mhchem@shortrightlongleftharpoons@pgf[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex]
        (0.5em,0.575ex+0.22ex) -- ++(#1-1em,0cm) arc (250:198:0.9ex);  
    \draw[cap=round, join=round, line width=0.09ex]
        (#1,0.575ex-0.22ex) -- ++(-#1,0cm) arc (70:18:0.9ex);
  \end{tikzpicture}%
}%

%%% for pgf-filled arrows
\newcommand*\mhchem@rightarrow@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (#1,0.575ex)
      -- ++(-0.6ex,0.2ex) -- ++(0.15ex,-0.2ex)
      -- ++(-0.15ex,-0.2ex)
      -- cycle;
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftarrow@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (0cm,0.575ex)
      -- ++(0.6ex,0.2ex) -- ++(-0.15ex,-0.2ex)
      -- ++(+0.15ex,-0.2ex)
      -- cycle;
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftrightarrow@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,0.85ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (#1,0.575ex)
      -- ++(-0.6ex,0.2ex) -- ++(0.15ex,-0.2ex)
      -- ++(-0.15ex,-0.2ex)
      -- cycle;
    \filldraw[cap=round, join=round, line width=0.09ex]
      (0cm,0.575ex)
      -- ++(0.6ex,0.2ex) -- ++(-0.15ex,-0.2ex)
      -- ++(+0.15ex,-0.2ex)
      -- cycle;      
  \end{tikzpicture}%
}%
\newcommand*\mhchem@leftrightharpoon@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex+0.22ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (#1,0.575ex+0.22ex)
      -- ++(-0.6ex,0.25ex) -- ++(0.15ex,-0.25ex)
      -- cycle;
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex-0.22ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (0cm,0.575ex-0.22ex)
      -- ++(0.6ex,-0.25ex) -- ++(-0.15ex,0.25ex)
      -- cycle;
  \end{tikzpicture}%
}%      
\newcommand*\mhchem@longrightshortleftharpoons@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex+0.22ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (#1,0.575ex+0.22ex)
      -- ++(-0.6ex,0.25ex) -- ++(0.15ex,-0.25ex)
      -- cycle;
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0.5em,0.575ex-0.22ex) -- ++(#1-1em,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (0.5em,0.575ex-0.22ex)
      -- ++(0.6ex,-0.25ex) -- ++(-0.15ex,0.25ex)
      -- cycle;
  \end{tikzpicture}%
}% 
\newcommand*\mhchem@shortrightlongleftharpoons@pgffilled[1]{%
  \begin{tikzpicture}[baseline]%
    \draw[use as bounding box] (0,0) (#1,1ex);
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0.5em,0.575ex+0.22ex) -- ++(#1-1em,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (#1-0.5em,0.575ex+0.22ex)
      -- ++(-0.6ex,0.25ex) -- ++(0.15ex,-0.25ex)
      -- cycle;
    \draw[cap=round, join=round, line width=0.09ex, shorten >=0.01ex]
      (0cm,0.575ex-0.22ex) -- ++(#1,0cm);
    \filldraw[cap=round, join=round, line width=0.09ex]
      (0cm,0.575ex-0.22ex)
      -- ++(0.6ex,-0.25ex) -- ++(-0.15ex,0.25ex)
      -- cycle;
  \end{tikzpicture}%
}%

\newlength{\mhchem@arrowlength@pgf}
\newlength{\mhchem@arrowminlength@pgf}
%TODO: use \mhchem@arrowminlength
\def\mhchem@labeledarrow@pgf#1#2#3#4#5#6#7{% 1-4 muskips 5 arrow 6 text above 7 below
  \setlength\mhchem@arrowlength@pgf{\widthof{\ensuremath{%
    \mkern#3mu%
    \mathop{}%
    \limits%
    \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                       #7\if0#2\else\mkern#2mu\fi}}%
    \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                       #6\if0#2\else\mkern#2mu\fi}}%	        
    \mkern#4mu%
  }}}%
  %
  \setlength\mhchem@arrowminlength@pgf{10pt+0.5em}%
  \ifthenelse{\equal{mhchem@longrightshortleftharpoons@pgf}{#5}}{
    \setlength\mhchem@arrowminlength@pgf{1.85em}%
    \setlength\mhchem@arrowlength@pgf{\widthof{\ensuremath{%
      \mkern#3mu%
      \mathop{}%
      \limits%
      \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                         #7\if0#2\else\mkern#2mu\fi}}%
      \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                         \hspace{1em}% %%
                         #6\if0#2\else\mkern#2mu\fi}}%	        
      \mkern#4mu%
    }}}%
  }{}%
  \ifthenelse{\equal{mhchem@shortrightlongleftharpoons@pgf}{#5}}{
    \setlength\mhchem@arrowminlength@pgf{1.85em}%
    \setlength\mhchem@arrowlength@pgf{\widthof{\ensuremath{%
      \mkern#3mu%
      \mathop{}%
      \limits%
      \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                         \hspace{1em}% %%
                         #7\if0#2\else\mkern#2mu\fi}}%
      \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                         #6\if0#2\else\mkern#2mu\fi}}%	        
      \mkern#4mu%
    }}}%
  }{}%
  \ifthenelse{\equal{mhchem@longrightshortleftharpoons@pgffilled}{#5}}{
    \setlength\mhchem@arrowminlength@pgf{1.85em}%
    \setlength\mhchem@arrowlength@pgf{\widthof{\ensuremath{%
      \mkern#3mu%
      \mathop{}%
      \limits%
      \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                         #7\if0#2\else\mkern#2mu\fi}}%
      \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                         \hspace{1em}% %%
                         #6\if0#2\else\mkern#2mu\fi}}%	        
      \mkern#4mu%
    }}}%
  }{}%
  \ifthenelse{\equal{mhchem@shortrightlongleftharpoons@pgffilled}{#5}}{
    \setlength\mhchem@arrowminlength@pgf{1.85em}%
    \setlength\mhchem@arrowlength@pgf{\widthof{\ensuremath{%
      \mkern#3mu%
      \mathop{}%
      \limits%
      \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                         \hspace{1em}% %%
                         #7\if0#2\else\mkern#2mu\fi}}%
      \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                         #6\if0#2\else\mkern#2mu\fi}}%	        
      \mkern#4mu%
    }}}%
  }{}%  
  %	        
  \ifdim\mhchem@arrowlength@pgf<\mhchem@arrowminlength@pgf%
    \setlength\mhchem@arrowlength@pgf{\mhchem@arrowminlength@pgf}%
  \fi%
  \mathrel{\mkern#3mu\mathop{\csname#5\endcsname{\mhchem@arrowlength@pgf}%
    }%
    \limits
    \@ifnotempty{#7}{^{\if0#1\else\mkern#1mu\fi%
                       #7\if0#2\else\mkern#2mu\fi}}%
    \@ifnotempty{#6}{_{\if0#1\else\mkern#1mu\fi%
                       #6\if0#2\else\mkern#2mu\fi}}%
    \mkern#4mu%
    }%}
}%       
	  		  
\newcommandtwoopt*\mhchem@gives[2][][]{}
\newcommandtwoopt*\mhchem@givesleft[2][][]{}
\newcommandtwoopt*\mhchem@mesomeric[2][][]{}
\newcommandtwoopt*\mhchem@equilibrium[2][][]{}
\newcommandtwoopt*\mhchem@equilibriumRight[2][][]{}
\newcommandtwoopt*\mhchem@equilibriumLeft[2][][]{}

\newcommand\mhchem@definearrows[1]{%
  %%% font
  \ifthenelse{\equal{#1}{font}}{%
		\renewcommandtwoopt*\mhchem@gives[2][\hspace{\mhchem@arrowminlength}][]{\ensuremath{%
		  \xrightarrow%
		    [{##2}]%
		    {##1}}}%
		\renewcommandtwoopt*\mhchem@givesleft[2][\hspace{\mhchem@arrowminlength}][]{\ensuremath{%
		  \xleftarrow%
		    [{##2}]%
		    {##1}}}%
		\renewcommandtwoopt*\mhchem@mesomeric[2][\hspace{\mhchem@arrowminlength}][]{\ensuremath{%
		  \ext@arrow 3399\leftrightarrowfill@%
		  {##2}%
		  {##1}}}%
		\renewcommandtwoopt*{\mhchem@equilibrium}[2][\hspace{\mhchem@arrowminlength}][]{\ensuremath{%
		  \mhchem@xrightleftharpoons%
		  [{##2}]%
		  {##1}}}%
		\renewcommandtwoopt*{\mhchem@equilibriumRight}[2][\hphantom{\makebox[\mhchem@arrowminlength]{}}][]{\ensuremath{%
		  \mhchem@xlongrightshortleftharpoons%
		  [{##2}]%
		  {##1}}}%
    \renewcommandtwoopt*{\mhchem@equilibriumLeft}[2][][\hspace{\mhchem@arrowminlength}]{\ensuremath{%
		  \mhchem@xshortrightlongleftharpoons%
		  [{##2}]%
		  {##1}}}%
  }{%%% pgf
    \ifthenelse{\equal{#1}{pgf}}{%
	    \renewcommandtwoopt*\mhchem@gives[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{1.5}{5}{1.5}{1}{mhchem@rightarrow@pgf}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@givesleft[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{5}{1.5}{1}{1.5}{mhchem@leftarrow@pgf}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@mesomeric[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{5}{5}{1}{1}{mhchem@leftrightarrow@pgf}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibrium[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{6}{6}{1}{1}{mhchem@leftrightharpoon@pgf}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibriumRight[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{6}{6}{1}{1}{mhchem@longrightshortleftharpoons@pgf}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibriumLeft[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{6}{6}{1}{1}{mhchem@shortrightlongleftharpoons@pgf}{##2}{##1}}}%
  }{%%% pgf-filled
    \ifthenelse{\equal{#1}{pgf-filled}}{%
	    \renewcommandtwoopt*\mhchem@gives[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{1.5}{7}{1.5}{1}{mhchem@rightarrow@pgffilled}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@givesleft[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{7}{1.5}{1}{1.5}{mhchem@leftarrow@pgffilled}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@mesomeric[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{7}{7}{1}{1}{mhchem@leftrightarrow@pgffilled}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibrium[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{7}{7}{1}{1}{mhchem@leftrightharpoon@pgffilled}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibriumRight[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{7}{7}{1}{1}{mhchem@longrightshortleftharpoons@pgffilled}{##2}{##1}}}%
	    \renewcommandtwoopt*\mhchem@equilibriumLeft[2][][]%
	      {\ensuremath{\mhchem@labeledarrow@pgf{7}{7}{1}{1}{mhchem@shortrightlongleftharpoons@pgffilled}{##2}{##1}}}%
	 	}{%
	    \PackageError{mhchem}{The option font=#1 is not supported}%
	  }%
  }}%
}

\newcommandtwoopt*\mhchem@givesT[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@gives[\text{#1}][\text{#2}]}%
\newcommandtwoopt*\mhchem@givesC[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@gives[\ce@main{#1}][\ce@main{#2}]}%
\newcommandtwoopt*\mhchem@givesleftT[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@givesleft[\text{#1}][\text{#2}]}%
\newcommandtwoopt*\mhchem@givesleftC[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@givesleft[\ce@main{#1}][\ce@main{#2}]}%
\newcommandtwoopt*\mhchem@mesomericT[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@mesomeric[\text{#1}][\text{#2}]}%
\newcommandtwoopt*\mhchem@mesomericC[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@mesomeric[\ce@main{#1}][\ce@main{#2}]}%
\newcommandtwoopt*{\mhchem@equilibriumT}[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@equilibrium[\text{#1}][\text{#2}]}
\newcommandtwoopt*{\mhchem@equilibriumC}[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@equilibrium[\ce@main{#1}][\ce@main{#2}]}
\newcommandtwoopt*{\mhchem@equilibriumRightT}[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@equilibriumRight[\text{#1}][\text{#2}]}
\newcommandtwoopt*{\mhchem@equilibriumRightC}[2][\hspace{\mhchem@arrowminlength}][]%
  {\mhchem@equilibriumRight[\ce@main{#1}][\ce@main{#2}]}
\newcommandtwoopt*{\mhchem@equilibriumLeftT}[2][][\hspace{\mhchem@arrowminlength}]%
  {\mhchem@equilibriumLeft[\text{#1}][\text{#2}]}
\newcommandtwoopt*{\mhchem@equilibriumLeftC}[2][][\hspace{\mhchem@arrowminlength}]%
  {\mhchem@equilibriumLeft[\ce@main{#1}][\ce@main{#2}]}


%%%%%%%%%%
% bonds - basic definition see in \cf
\newlength\mhchem@bondwidth%
\newlength\mhchem@bondheight%
\newlength\mhchem@smallbondwidth@tmpA%
\newlength\mhchem@smallbondwidth@tmpB%
\newlength\mhchem@smallbondwidth%

\def\mhchem@setbondwidth{%
  \setlength\mhchem@bondwidth{\widthof{\sbond}}%
  \setlength\mhchem@bondheight{\heightof{\sbond}}%
  \setlength\mhchem@smallbondwidth@tmpA{%
    \mhchem@bondwidth-\mhchem@option@minussidebearingleft-\mhchem@option@minussidebearingright}%
  \setlength\mhchem@smallbondwidth@tmpB{%
    \widthof{\sbond\sbond\sbond}-\mhchem@option@minussidebearingleft-%
    \mhchem@option@minussidebearingright}%
  \setlength\mhchem@smallbondwidth{\mhchem@bondwidth*%
    \ratio{\mhchem@smallbondwidth@tmpA}{\mhchem@smallbondwidth@tmpB}}%
}
\def\mhchem@halfbond{\rlap{\hspace{\mhchem@option@minussidebearingleft}%
                     \resizebox{\mhchem@smallbondwidth}{\mhchem@bondheight}{\sbond}\unskip%
                     \resizebox{\mhchem@smallbondwidth}{\mhchem@bondheight}{\sbond}%
                     \resizebox{\mhchem@smallbondwidth}{\mhchem@bondheight}{\sbond}}%
                     \phantom{\sbond}}
\def\mhchem@bond#1{%
  \mhchem@cf@length{#1}%
  {}%
  \ifnum\value{mhchem@cf@length}>1\relax%
    \ifthenelse{\equal{#1}{~-}}{%
      \mhchem@setbondwidth%
      \rlap{\protect\raisebox{.2ex}{\mhchem@halfbond}}%
      \protect\raisebox{-.2ex}{\sbond}}{%
    \ifthenelse{\equal{#1}{~--}}{%            
      \mhchem@setbondwidth%
      \rlap{\protect\raisebox{.4ex}{\mhchem@halfbond}}%
	    \rlap{\sbond}%
	    \protect\raisebox{-.4ex}{\sbond}}{%
    \ifthenelse{\equal{#1}{~=}}{%            
      \mhchem@setbondwidth%
      \rlap{\protect\raisebox{.4ex}{\mhchem@halfbond}}%
	    \rlap{\sbond}%
	    \protect\raisebox{-.4ex}{\sbond}}{%
    \ifthenelse{\equal{#1}{-~-}}{%            
      \mhchem@setbondwidth%
      \rlap{\protect\raisebox{.4ex}{\sbond}}%
	    \rlap{\mhchem@halfbond}%
	    \protect\raisebox{-.4ex}{\sbond}}{%
    \ifthenelse{\equal{#1}{...}}{{\cdot}{\cdot}{\cdot}}{%
    \ifthenelse{\equal{#1}{....}}{{\cdot}{\cdot}{\cdot}{\cdot}}{%
    \ifthenelse{\equal{#1}{->}}{{\rightarrow}}{%
    \ifthenelse{\equal{#1}{<-}}{{\leftarrow}}{%
    %
      \PackageError{mhchem}{unknown bond type in \string\bond}%
    }}}}}}}}%
  \else%
    \if\noexpand#1##%
      \tbond%
    \else%
      \ifthenelse{\equal{#1}{-}}{\sbond}{%
      \ifthenelse{\equal{#1}{=}}{\dbond}{%
      \ifthenelse{\equal{#1}{\tbond}}{\tbond}{%
      \ifthenelse{\equal{#1}{~}}{%
        \mhchem@setbondwidth%
        \mhchem@halfbond}{%
      %
        \PackageError{mhchem}{unknown bond type in \string\bond}%
      }}}}%
    \fi%
  \fi%
}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   \cf   %%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newtoks\mhchem@cf@element%
\newtoks\mhchem@cf@number%
\newtoks\mhchem@cf@sup%
\newtoks\tok@mhchem@cf@i%

\newcommand*{\cf}[2][]{%
	\bgroup%
	\def\sbond{{\ensuremath{-}}}%
	\DeclareRobustCommand\dbond{\rlap{\protect\raisebox{.2ex}{\sbond}}\protect\raisebox{-.2ex}{\sbond}}%
	\def\tbond{\rlap{\protect\raisebox{.4ex}{\sbond}}%
    \rlap{\sbond}\protect\raisebox{-.4ex}{\sbond}}%
	\def\hyphen{\mhchem@hyphen}%
	\ifmmode\else\def\mhchem@option@alwaystextmode{1}\fi%
	\if 1\mhchem@option@alwaystextmode%
	  \edef\mhchem@mathortext##1{\noexpand\text{##1}}%
	  \edef\mhchem@mathortext@ii##1##2{##2}%
	\else%
	  \ifnum1<\mhchem@option@version%
	    \edef\mhchem@mathortext##1{\ifmmode\noexpand\mhchem@option@mathfont{##1}\else\noexpand\text{##1}\fi}%
	    \edef\mhchem@mathortext@ii##1##2{\ifmmode\noexpand\mhchem@option@mathfont{##1}\else ##2\fi}%
	  \else
      \edef\mhchem@mathortext##1{\ifmmode ##1\else\noexpand\text{##1}\fi}%
      \edef\mhchem@mathortext@ii##1##2{\ifmmode ##1\else ##2\fi}%
	  \fi%
	\fi%
	\ifmmode\else\mhchem@option@textfont\fi%
	\ensuremath{%
	%
	%
	%
	\def\mhchem@cf@presub{}%
	\def\mhchem@cf@presup{}%
	\def\mhchem@cf@others{}%
	\def\mhchem@cf@state{s}%
%
%
%
%
%
%
%
%
  \ifthenelse{\equal{#1}{}}%
    {\mhchem@cf@i #2\mhchem@END\mhchem@ENDEND}%
    {\ensuremath{\overset{#1}{\mhchem@cf@i #2\mhchem@END\mhchem@ENDEND}}}%
  %TODO: insert kerning if full stop (or similar) follows superscript
  %\@ifnextchar,{\kern-0.2em}{} ??%
 }\egroup%
}
\def\mhchem@cf@output{%
  \if\mhchem@cf@state s%
    %
  \else\if\mhchem@cf@state 1%
    {\mhchem@mathortext{\expandafter\mhchem@cf@frac\the\mhchem@cf@number/\mhchem@END}}%
  \else\if\mhchem@cf@state n%
    {\mhchem@mathortext{\expandafter\mhchem@cf@frac\the\mhchem@cf@number/\mhchem@END}}%
  \else\if\mhchem@cf@state M%
    \mhchem@cmath{\the\mhchem@cf@element}
  \else%
    \if\mhchem@option@usenonsimultaneoussubsuperscripts 0%
      \mhchem@chemfive{\mhchem@cf@presup}{\mhchem@cf@presub}%
        {\the\mhchem@cf@element}{\the\mhchem@cf@number}{\the\mhchem@cf@sup}{}%
    \else%
      \mhchem@chemfive{\mhchem@cf@presup}{\mhchem@cf@presub}%
        {\the\mhchem@cf@element}{\the\mhchem@cf@number}{}{\the\mhchem@cf@sup}%
    \fi%
  \fi\fi\fi\fi%
  \mhchem@cf@element{}
  \mhchem@cf@number{}%
  \mhchem@cf@sup{}%
  \def\mhchem@cf@presub{}%
  \def\mhchem@cf@presup{}%
  \def\mhchem@cf@others{}%
}
\def\mhchem@cf@output@o#1{%
  \mhchem@cf@output%
  \if\mhchem@cf@state s\else\nolinebreak\fi%
  {#1}%
}

\newcounter{mhchem@cf@length}%
\def\mhchem@cf@length#1{%
  \setcounter{mhchem@cf@length}{0}%
  \ifx\@empty#1\@empty%
  \else%
    \setcounter{mhchem@cf@length}{1}%
    \mhchem@cf@length@i#1\mhchem@END%
  \fi%
}
\def\mhchem@cf@length@i#1#2\mhchem@END{%
  \ifx\@empty#2\@empty%
  \else%
    \setcounter{mhchem@cf@length}{2}%
  \fi%
}

\def\mhchem@cf@frac#1/#2\mhchem@END{\ifthenelse{\equal{#2}{}}{#1\,}{%
  \ensuremath{\mathchoice%
    {\textstyle%
     \frac{\mhchem@mathortext{#1}}{\mhchem@mathortext{\mhchem@getfirstchar#2\mhchem@ENDgetfirstchar}}\mskip1mu}%
    {\frac{\mhchem@mathortext{#1}}{\mhchem@mathortext{\mhchem@getfirstchar#2\mhchem@ENDgetfirstchar}}\mskip1mu}%
    {\frac{\mhchem@mathortext{#1}}{\mhchem@mathortext{\mhchem@getfirstchar#2\mhchem@ENDgetfirstchar}}\mskip1mu}%
    {\frac{\mhchem@mathortext{#1}}{\mhchem@mathortext{\mhchem@getfirstchar#2\mhchem@ENDgetfirstchar}}\mskip1mu}}}}
\def\mhchem@getfirstchar#1#2\mhchem@ENDgetfirstchar{#1}
\def\mhchem@getlastchars#1#2\mhchem@ENDgetlastchars{#2}

\newtoks\mhchem@cf@replaceminus@tok
\def\mhchem@cf@replaceminus#1{%
  \mhchem@cf@replaceminus@tok{}%
  \mhchem@cf@replaceminus@i#1-\mhchem@END\mhchem@ENDEND%
  \the\mhchem@cf@replaceminus@tok}
\def\mhchem@cf@replaceminus@i#1-#2\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    \mhchem@cf@replaceminus@tok=\expandafter{\the\mhchem@cf@replaceminus@tok#1}%
  \else%
    \mhchem@cf@replaceminus@tok=\expandafter{#1\mhchem@mathortext@ii{-}{$\,$--$\,$}}%\ensuremath{-}%
    \mhchem@cf@replaceminus@i#2\mhchem@ENDEND%
  \fi%
}

\def\mhchem@cf@replacedot#1{\mhchem@cf@replacedot@i#1.\mhchem@END\mhchem@ENDEND}
\def\mhchem@cf@replacedot@i#1.#2\mhchem@ENDEND{%
  \ifx\mhchem@END#2%
    #1%
  \else%
    #1%{\noexpand\textbf{\noexpand\fontfamily{cmr}\noexpand\selectfont\noexpand\textperiodcentered}}%
      {\textbf{\fontfamily{cmr}\selectfont\textperiodcentered}}%
    \mhchem@cf@replacedot@i#2\mhchem@ENDEND%
  \fi%
}

\def\mhchem@cf@i#1#2\mhchem@ENDEND{%
  \ifx\mhchem@END#1%
    \mhchem@cf@output%
  \else%
      \ifx\@empty#1\@empty% leer
        \if\mhchem@cf@state e\def\mhchem@cf@state{+}%
        \else\if\mhchem@cf@state E\def\mhchem@cf@state{+}%
        \else\if\mhchem@cf@state p\def\mhchem@cf@state{*}%
        \else\if\mhchem@cf@state P\def\mhchem@cf@state{*}%
        \else\if\mhchem@cf@state f\def\mhchem@cf@state{+}%
        \else\if\mhchem@cf@state F\def\mhchem@cf@state{+}%
        \else\if\mhchem@cf@state q\def\mhchem@cf@state{*}%
        \else\if\mhchem@cf@state Q\def\mhchem@cf@state{*}%
        \else%
          \mhchem@cf@output%
          \def\mhchem@cf@state{s}%
        \fi\fi\fi\fi\fi\fi\fi\fi%
      \else\ifx\protect#1%
      \else\if\mhchem@cf@state e%
        \mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup%
          \expandafter\mhchem@cf@replacedot\expandafter{\mhchem@cf@replaceminus{#1}}}%
        \def\mhchem@cf@state{+}%
      \else\if\mhchem@cf@state E%
        \mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup%
          \mhchem@mathortext@ii{\mhchem@option@mathfont{#1}}{#1}}%
        \def\mhchem@cf@state{+}%
      \else\if\mhchem@cf@state p%
        \g@addto@macro\mhchem@cf@presup{#1}%
        \def\mhchem@cf@state{*}%
      \else\if\mhchem@cf@state P%
        \edef\mhchem@cf@presup{\mhchem@cf@presup%
          \mhchem@mathortext@ii{\mhchem@option@mathfont{#1}}{#1}}%
        \def\mhchem@cf@state{*}%
      \else\if\mhchem@cf@state f%
        \mhchem@cf@number=\expandafter{\the\mhchem@cf@number#1}%
        \def\mhchem@cf@state{+}%
      \else\if\mhchem@cf@state F%
        \ifx\@empty\the\mhchem@cf@number\@empty%***
        \else\mhchem@cf@number=\expandafter{\the\mhchem@cf@number\,}\fi%
        \mhchem@cf@number=\expandafter{\the\mhchem@cf@number%
          \mhchem@mathortext@ii{\mhchem@option@mathfont{#1}}{#1}}%
        \def\mhchem@cf@state{+}%
      \else\if\mhchem@cf@state q%
        \g@addto@macro\mhchem@cf@presub{#1}%
        \def\mhchem@cf@state{*}%
      \else\if\mhchem@cf@state Q%
        \edef\mhchem@cf@presub{\mhchem@cf@presub%
          \mhchem@mathortext@ii{\mhchem@option@mathfont{#1}}{#1}}%
        \def\mhchem@cf@state{*}%
      \else\if\mhchem@cf@state m%
        \mhchem@cmath{#1}%
        \def\mhchem@cf@state{+}%
      \else\if\mhchem@cf@state b%
        \mhchem@bond{#1}%
        \def\mhchem@cf@state{+}%
      \else%
        \mhchem@cf@length{#1}%
        \ifnum\value{mhchem@cf@length}>1%
          \if\mhchem@cf@state M%
            \mhchem@cf@element=\expandafter{\the\mhchem@cf@element{#1}}%
          \else%
            \mhchem@cf@output@o{#1}%
          \fi%
        \else%
          \if\mhchem@cf@state M%
            \ifcat$\noexpand#1%
              \mhchem@cf@output%
              \def\mhchem@cf@state{+}%
            \else%
              \mhchem@cf@element=\expandafter{\the\mhchem@cf@element#1}%
            \fi%
          \else\ifx\ #1\mhchem@cf@output%
          \else\ifx\protect#1%
          \else\ifx#1\cmath%
            \mhchem@cf@output%
            \def\mhchem@cf@state{m}%
          \else\ifx#1\bond%
            \ifnum2<\mhchem@option@version%
              \mhchem@cf@output%
              \def\mhchem@cf@state{b}%
            \else%
              \mhchem@cf@output%
              \sbond%
            \fi%
          \else\if\noexpand#1`%
            \if\mhchem@cf@state s\def\mhchem@cf@state{P}%
            \else\if\mhchem@cf@state 1\mhchem@cf@output\def\mhchem@cf@state{P}%
            \else\if\mhchem@cf@state *\def\mhchem@cf@state{P}%
            \else\def\mhchem@cf@state{E}%
            \fi\fi\fi%
          \else\if\noexpand#1,%
            \if\mhchem@cf@state s\def\mhchem@cf@state{Q}%
            \else\if\mhchem@cf@state 1\mhchem@cf@output\def\mhchem@cf@state{Q}%
            \else\if\mhchem@cf@state *\def\mhchem@cf@state{Q}%
            \else\def\mhchem@cf@state{F}%
            \fi\fi\fi%
          \else\ifx#1(%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1)%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1[%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1]%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1\{%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1\}%
            \mhchem@cf@output@o{\mhchem@mathortext{#1}}%
          \else\ifx#1+%
            \mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup #1}%
            \def\mhchem@cf@state{+}%
          \else\ifx#1-%
            \ifnum1<\mhchem@option@version%
              \ifx\mhchem@END#2%
                \mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup \mhchem@cf@replaceminus{#1}}%
                \def\mhchem@cf@state{+}%
              \else%
                \mhchem@cf@output%
                \sbond%
              \fi%
            \else%
              \mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup \mhchem@cf@replaceminus{#1}}%
              \def\mhchem@cf@state{+}%
            \fi%
          \else\ifx#1=%
            \ifnum1<\mhchem@option@version%
              \mhchem@cf@output%
              \dbond%
            \else%
              \mhchem@cf@output@o{#1}%
            \fi%
          \else\if\noexpand#1##%
            \ifnum1<\mhchem@option@version%
              \mhchem@cf@output%
              \tbond%
            \else%
              \mhchem@cf@output@o{\#}%
            \fi%
          \else\ifx#1.%
            \mhchem@cf@output%
            \mhchem@mathortext@ii{\cdot}{\,\ensuremath{{\cdot}}\,}%
            \def\mhchem@cf@state{s}%
          \else\ifx#1*%
            \mhchem@cf@output%
            \mhchem@mathortext@ii{\cdot}{\,\ensuremath{{\cdot}}\,}%
            \def\mhchem@cf@state{s}%
          \else\ifcat 1\noexpand#1%
            \if\mhchem@cf@state 2%
            \else%
              \if\mhchem@cf@state s%
                \def\mhchem@cf@state{1}%
              \else\if\mhchem@cf@state 1%
              \else%
                \def\mhchem@cf@state{2}%
              \fi\fi%
            \fi%
            \mhchem@cf@number=\expandafter{\the\mhchem@cf@number #1}%
          \else\ifcat a\noexpand#1%
            \if\mhchem@cf@state a%
            \else%
              \if\mhchem@cf@state *\else\mhchem@cf@output%
                \if\mhchem@cf@state s\else%
                   \nolinebreak%
                \fi%
              \fi%
              \def\mhchem@cf@state{a}%
            \fi%
            \mhchem@cf@element=\expandafter{\the\mhchem@cf@element#1}%
          \else%
            \ifcat ^\noexpand#1%
              \if\mhchem@cf@state s\def\mhchem@cf@state{p}%
              \else\if\mhchem@cf@state 1\mhchem@cf@output\def\mhchem@cf@state{p}%
              \else\if\mhchem@cf@state *\def\mhchem@cf@state{p}%
              \else%
                \ifx\@empty\the\mhchem@cf@sup\@empty%***
                  \else\mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup\,}\fi%
                \def\mhchem@cf@state{e}%
              \fi\fi\fi%
            \else\if^\noexpand#1%
              \if\mhchem@cf@state s\def\mhchem@cf@state{p}%
              \else\if\mhchem@cf@state 1\mhchem@cf@output\def\mhchem@cf@state{p}%
              \else\if\mhchem@cf@state *\def\mhchem@cf@state{p}%
              \else%
                \ifx\@empty\the\mhchem@cf@sup\@empty%***
                  \else\mhchem@cf@sup=\expandafter{\the\mhchem@cf@sup\,}\fi%
                \def\mhchem@cf@state{e}%
              \fi\fi\fi%
            \else\ifcat _\noexpand#1%
              \if\mhchem@cf@state s\def\mhchem@cf@state{q}%
              \else\if\mhchem@cf@state 1\mhchem@cf@output\def\mhchem@cf@state{q}%
              \else\if\mhchem@cf@state *\def\mhchem@cf@state{q}%
              \else\if\mhchem@cf@state 2\mhchem@cf@number=\expandafter{\the\mhchem@cf@number\,}\def\mhchem@cf@state{f}%
              \else\def\mhchem@cf@state{f}%
              \fi\fi\fi\fi%
            \else\ifcat$\noexpand#1%
              \mhchem@cf@output%
              \def\mhchem@cf@state{M}%
            \else%
              \mhchem@cf@output@o{#1}%
            \fi\fi\fi\fi%
          \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi%
        \fi%
      \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi\fi%
      \mhchem@cf@length{#2}%
      \mhchem@cf@i #2\mhchem@ENDEND%
  \fi%
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   \mhchem@chemfive   %%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\newcommand*{\mhchem@chemfive}[6]{%
%
  \def\mhchem@largest@superscript{\smash[t]{2+}}% [4]
  \def\mhchem@vphantommathortext##1{\vphantom{\mhchem@mathortext{##1}}}% [2][5]
  \m@th%
  \ensuremath{%
    \ifthenelse{\equal{#1#2}{}}{}{%
      \setlength{\dimen0}{\widthof{${}^{%
        \mhchem@mathortext{% [5]
          #1% [1]
        }% [5]
      }$}}% [1]
      \setlength{\dimen1}{\widthof{${}_{#2}$}}% [1]
      \ifdim\dimen0<\dimen1\setlength{\dimen0}{\dimen1}\fi% [1]
      \makebox{\vphantom{\text{#3}}}% [2]
      {}%
      ^{%
        \mhchem@mathboxright{\dimen0}{% [1]
          \mhchem@vphantommathortext{#5#6}% [2][5]
          \mhchem@vphantommathortext{\mhchem@largest@superscript}% [4][5]
          \mhchem@mathortext{% [5]
            #1%
          }% [5]
        }% [1]
       }%
      _{%
        \mhchem@mathboxright{\dimen0}{% [1]
          \mhchem@vphantommathortext{#4}% [2][5]
          \mhchem@mathortext{% [5]
            #2%
          }% [5]
        }% [1]
       }%
      \mhchem@minispace% [3]
    }%
    \mhchem@mathortext@ii{% [5]
      \mhchem@option@mathfont {#3}%
      }{\text{#3}}% [5]
    \ifthenelse{\equal{#4#5}{}}{}{%
      _{%
        \mhchem@vphantommathortext{#2}% [2][5]
        \mhchem@mathortext{% [5]
          #4%
        }% [5]
       }%
      ^{%
        \mhchem@vphantommathortext{#1#6}% [2][5]
        \mhchem@vphantommathortext{\mhchem@largest@superscript}% [4][5]
        \mhchem@mathortext{% [5]
          #5%
        }% [5]
       }%
    }%
    \ifthenelse{\equal{#6}{}}{}{%
      \mhchem@minispace% [3]
      {}%
      _{\mhchem@vphantommathortext{#2#4}}% [2][5]
      ^{%
        \mhchem@vphantommathortext{#1#5}% [2][5]
        \mhchem@vphantommathortext{\mhchem@largest@superscript}% [4][5]
        \mhchem@mathortext{% [5]
          #6%
        }% [5]
       }%
    }%
  }%
%
%
%
%
%
%
%
%
}

\newcommand*\mhchem@mathbox[2][]{%
  \mathchoice%
    {\mhchem@mathbox@ii{\displaystyle}{#1}{#2}}%
    {\mhchem@mathbox@ii{\textstyle}{#1}{#2}}%
    {\mhchem@mathbox@ii{\scriptstyle}{#1}{#2}}%
    {\mhchem@mathbox@ii{\scriptscriptstyle}{#1}{#2}}}%
\newcommand*\mhchem@mathbox@ii[3]{%    
  \setlength{\dimen1}{\widthof{\ensuremath{#1#2}}}%
  \setlength{\dimen2}{\widthof{\ensuremath{#1#3}}}%
  \ifdim\dimen1<\dimen2%
    \mhchem@mathbox@i{#3}%
  \else%
    \makebox[\dimen1]{\ensuremath{#1#3}}%
  \fi}
\newcommand*\mhchem@mathbox@i[1]{\mathchoice%
  {\mbox{\ensuremath{\displaystyle#1}}}%
  {\mbox{\ensuremath{\textstyle#1}}}%
  {\mbox{\ensuremath{\scriptstyle#1}}}%
  {\mbox{\ensuremath{\scriptscriptstyle#1}}}}
  
\newcommand*\mhchem@mathboxright[2]{\mathchoice%
  {\makebox[#1][r]{\ensuremath{\displaystyle#2}}}%
  {\makebox[#1][r]{\ensuremath{\textstyle#2}}}%
  {\makebox[#1][r]{\ensuremath{\scriptstyle#2}}}%
  {\makebox[#1][r]{\ensuremath{\scriptscriptstyle#2}}}}

\newcommand*\mhchem@minispace{%
  \setlength{\dimen2}{0pt-\widthof{${}^8_8$}+%
             \widthof{$\text{C}^8_8$}-\widthof{$\text{C}^{}_{}$}}% [3]
  \kern\dimen2%
              %
              %
}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%   Options   %%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\mhchem@option@version{0}
\define@key{mhchem}{version}{\def\mhchem@option@version{#1}}

\def\mhchem@option@mathfont{\mathrm}
\def\mhchem@option@textfont{}
\define@key{mhchem}{textfontcommand}{\def\mhchem@option@textfont{#1}}
\define@key{mhchem}{textfontname}{\def\mhchem@option@textfont{\csname#1\endcsname}}
\define@key{mhchem}{mathfontcommand}{\def\mhchem@option@mathfont{#1}}
\define@key{mhchem}{mathfontname}{\def\mhchem@option@mathfont{\csname#1\endcsname}}
\define@key{mhchem}{font}{%
  \ifthenelse{\equal{sf}{#1}}{%
    \def\mhchem@option@textfont{\sffamily}%
    \def\mhchem@option@mathfont{\mathsf}%
  }{\ifthenelse{\equal{}{#1}}{%
    \def\mhchem@option@textfont{}%
    \def\mhchem@option@mathfont{\mathrm}%
  }{\PackageError{mhchem}{Font option `#1' unknown}}}%
}

\newlength\mhchem@option@minussidebearingleft
\newlength\mhchem@option@minussidebearingright
\setlength\mhchem@option@minussidebearingleft{0.06em}
\setlength\mhchem@option@minussidebearingright{0.11em}
\define@key{mhchem}{minus-sidebearing-left}{\setlength\mhchem@option@minussidebearingleft{#1}}
\define@key{mhchem}{minus-sidebearing-right}{\setlength\mhchem@option@minussidebearingright{#1}}

%
%
%
%
%
%
%
%
%
%
%
%
%
%
%

\def\mhchem@option@usenonsimultaneoussubsuperscripts{0}%
\def\mhchem@option@alwaystextmode{0}%

\mhchem@definearrows{font}
\define@key{mhchem}{arrows}{%
  \ifthenelse{\equal{pgf}{#1} \or \equal{pgf-filled}{#1}}{% 
     \RequirePackage{pgf}% for finding the tikz package more easily
     \RequirePackage{tikz}%
  }{}%
  \mhchem@definearrows{#1}%
}

%%% begin: standard keyval handling as in many other packages 
\def\ProcessOptionsWithKV#1{%
  \let\@tempc\relax%
  \let\mhchem@tempa\@empty%
  \@for\CurrentOption:=\@classoptionslist\do{%
    \@ifundefined{KV@#1@\CurrentOption}%
    {}%
    {%
      \edef\mhchem@tempa{\mhchem@tempa,\CurrentOption,}%
      \@expandtwoargs\@removeelement\CurrentOption%
        \@unusedoptionlist\@unusedoptionlist%
    }%
  }%
  \edef\mhchem@tempa{%
    \noexpand\setkeys{#1}{%
      \mhchem@tempa\@ptionlist{\@currname.\@currext}%
    }%
  }%
  \mhchem@tempa%
  \let\CurrentOption\@empty%
  \AtEndOfPackage{\let\@unprocessedoptions\relax}%
}
\ProcessOptionsWithKV{mhchem}\relax
%%% end:

\define@key{mhchem}{arrows}{\mhchem@definearrows{#1}}

\newcommand*\mhchemoptions[1]{\setkeys{mhchem}{#1}}

\ifnum0=\mhchem@option@version%
  \PackageWarningNoLine{mhchem}{%
    You did not specify a 'version' option for the mhchem\MessageBreak
    package. This means you EITHER have an existing\MessageBreak
    document and mhchem was updated to a newer version.\MessageBreak
    Please check the mhchem manual in that case! OR, you\MessageBreak
    are about to create a new document; in this case,\MessageBreak
    please write \string\usepackage[version=3]{mhchem} in your preamble in\MessageBreak
    order to use the most recent version of mhchem}%
  \def\mhchem@option@version{1}%
\else%
\fi%










%TODO: option for CrO_4{}^{2-} instead of CrO_4^{2-} - proper switch option [wordstyle] and documentation
%TODO: option to use nicefrac
%TODO: option for automatically using nicefrac im text mode
%TODO: kerning if superscript is followed by arrow (inside ce), comma (outside) etc.
%TODO: make sure a \cf in a (uppercase) heading retains its mixed case
% from fancyhdr.sty  version 3.0:
% \def\nouppercase##1{{\let\uppercase\relax\let\MakeUppercase\relax
%     \expandafter\let\csname MakeUppercase \endcsname\relax##1}}%
%TODO: bold Parts of formulae?
%TODO: Option for longer arrows
%TODO: spacing? X2 Y ^2-  before ^
%TODO: always minimum length of arrows? override?
%TODO: count0 und dimen@ eliminieren
%
%
%

\def\mhchem@END{}
%\def\mhchem@ENDEND{}
\def\mhchem@empty{}